Radio link maintenance involving multiple uplink carriers

A method in a base station in dual connectivity mode for handling radio link failures (RLF), wherein the base station is connected to a User Equipment (UE) by of a plurality of uplink (UL) carriers;

• the method comprising:
• receiving from the UE retransmissions of a certain Radio Link Control (RLC) data packet that is transmitted on at least two of the plurality of UL carriers that are separate, wherein one link is a primary UL carrier and the other link is a supplementary UL (SUL) carrier;
• providing acknowledgement feedback to the UE for the retransmissions of the RLC data packet to enable common monitoring of the least two UL carriers at the UE using a single retransmission counter;
• receiving, from the UE, information indicative of a common RLF for both of the primary UL carrier and the SUL carrier in dual connectivity mode determined based on the signal retransmission counter;
• wherein the base station configures the UE to select a cell based on one or more of the following criteria:
• select a cell out of one or a plurality of cells that support a SUL carrier;
• select a cell based on measurements on both Downlink (DL) and UL radio link quality;
• select a cell only based on measurements of DL radio channel quality;
• and
• select a cell based on a load measurement of the cell, and the load of each carrier belonging to the same cell;
• and
• configuring a first cell with an SUL carrier and the primary UL carrier, and configuring a second cell without a SUL carrier;
• and
• configuring the UE to perform:
• measuring the DL and the UL radio link quality;
• determining if the DL radio link quality of both the first and second is above a certain minimum quality threshold and/or if the SUL carrier provides a larger path gain than that of the primary UL carrier;
• and
• based on the determining be in the affirmative, selecting the first cell.

A user equipment (UE) in dual connectivity mode for handling radio link failures (RLF);

• wherein the UE is connected to a radio communication network by of a plurality of uplink (UL) carriers;
• the UE comprising:
• processing circuitry;
• memory containing instructions executable by the processing circuitry whereby the UE is operative to:
• perform retransmissions of a certain Radio Link Control (RLC) data packet on at least two of the plurality of UL carriers that are separate, wherein one link is a primary UL carrier and the other link is a supplementary UL (SUL) carrier;
• monitor retransmissions of a RLC data packet commonly for the at least two UL carriers using a single retransmission counter for both of the primary UL carrier and the SUL carrier in dual connectivity mode;
• provide information indicative of a common RLF for the at least two UL carriers;
• wherein the UE is configured to select a cell based on one or more of the following criteria:
• select a cell out of one or a plurality of cells that support a SUL carrier;
• select a cell based on measurements on both Downlink (DL) and UL radio link quality;
• select a cell only based on measurements of the DL radio channel quality;
• and
• select a cell based on a load measurement of the cell, and the load of each carrier belonging to the same cell;
• and
• wherein, if a first cell is configured with a SUL carrier and the primary UL carrier, and a second cell is not configured with a SUL carrier, the UE performs:
• measuring DL radio link quality and UL radio link quality;
• determining if the DL radio link quality of both the first and second cells is above a certain minimum quality threshold and/or if the SUL carrier provides a larger path gain than that of the primary UL carrier;
• and
• based on the determining be in the affirmative, selecting the first cell.

A base station of a radio communications network in dual connectivity mode for handling radio link failures (RLF;

• wherein a UE is connected to the based station by of a plurality of uplink (UL) carriers;
• the base station comprising:
• processing circuitry;
• memory containing instructions executable by the processing circuitry whereby the base station is operative to:
• receive from the UE retransmissions of a certain Radio Link Control (RLC) data packet that is transmitted on at least two of the plurality of UL carriers that are separate, wherein one link is a primary UL carrier and the other link is a supplementary UL (SUL) carrier;
• provide acknowledgement feedback to the UE for the retransmissions of the RLC data packet to enable common monitoring of the least two UL carriers at the UE using a single retransmission counter;
• receive, from the UE, information indicative of a common RLF for both of the primary UL carrier and the SUL carrier in dual connectivity mode determined based on the single retransmission counter;
• wherein the base station configures the UE to select a cell based on one or more of the following criteria:
• select a cell out of one or a plurality of cells that support a SUL carrier;
• select a cell based on measurements on both Downlink (DL) and UL radio link quality;
• select a cell only based on measurements of DL radio channel quality;
• and
• select a cell based on a load measurement of the cell, and the load of each carrier belonging to the same cell;
• and
• configuring a first cell with an SUL carrier and the primary UL carrier, and configuring a second cell without a SUL carrier;
• and
• configuring the UE to perform:
• measuring the DL and the UL radio link quality;
• determining if the DL radio link quality of both the first and second is above a certain minimum quality threshold and/or if the SUL carrier provides a larger path gain than that of the primary UL carrier;
• and
• based on the determining be in the affirmative, selecting the first cell.